Testing for fetal exposure to illicit drugs using umbilical cord tissue vs meconium.

Objective: We assessed the agreement of testing for fetal exposure to illicit drugs contrasting paired specimens of meconium vs umbilical cord tissue.

Methods: We obtained paired samples of meconium and umbilical cord tissue from 118 pregnancies with high suspicion of illicit drug use by the mothers. Each specimen was tested for amphetamines, opiates, cocaine, cannabinoids, and phencyclidine using drug class-specific immunoassays.

Results: The agreement of drug screening results between cord and meconium was above 90% for all drugs tested. Meconium identified 21 cases as positive for amphetamines. The paired cord identified 20 of these, and in addition identified three other positives that the meconium labeled as negative. Gas chromatography-mass spectrometry confirmed these three cord samples as methamphetamine positive. Meconium identified 97 samples that were negative for amphetamines, while the cord identified 94 of these as negative but three as positive. Agreement of cord with meconium for amphetamines was 96.6%. The concordance for opiates was 94.9%, for cocaine was 99.2%, and for cannabinoids was 90.7%.

Conclusions: Umbilical cord tissue performs as well as meconium in assessing fetal drug exposure to amphetamines, opiates, cocaine, and cannabinoids. Results of studies using the cord may have a more rapid return to the clinician, because waiting for meconium to be passed sometimes requires several days. Moreover, in some cases the meconium is passed in utero making collection impossible, whereas cord should always be available for drug testing.